Method of forming a decorative wear resistant layer

ABSTRACT

A method to form a digital print on a substrate including a polymer material by bonding particles in powder form to the surface of the substrate. The method may include: providing a substrate including a thermoplastic material and a transparent layer including a thermoplastic material, providing a continuous print layer including particles on the substrate or on the transparent layer, printing a digital image including colour pigments on the print layer, and bonding the print layer with the colour pigments to the transparent layer and to the substrate with heat and pressure such that the digital image is located between the transparent layer and the substrate.

TECHNICAL FIELD

The disclosure generally relates to the field of digitally createddecorative surfaces for building panels such as floor and wall panels.The disclosure relates to a method of forming a print layer and to semifinished product and panels comprising such print layer.

FIELD OF THE APPLICATION

Embodiments of the present invention are particularly suitable for usein floors, which are formed of floor panels comprising a core, adecorative layer and preferably a transparent wear resistant structuredlayer above the decorative layer. Preferred embodiments are laminatefloors and plastic based LVT floors. The following description oftechniques, problems of known technology and objects and features of theinvention will therefore, as a non-restrictive example, be aimed aboveall at this field of application and in particular at floorings with aresilient surface layer.

It should be emphasized that embodiments of the invention may be used toproduce a digital image on any surface but flat panels such as forexample building panels in general, wall panels, ceilings, furniturecomponents and similar products that generally have large surfaces withadvanced decorative patterns are preferred. The basic principles of theinvention may be used to apply a digital print on dense surfaces such asplastic materials or metal foils and polymer impregnated or coated paperor foils.

BACKGROUND

The following description is used to describe the background andproducts, materials and production methods that may comprise specificparts of preferred embodiments in the disclosure of this invention.

The majority of all laminate floors are produced according to aproduction method generally referred to as Direct Pressed Laminate(DPL). Such laminated floors have a core of 6-12 mm fibreboard, a 0.2 mmthick upper decorative surface layer of laminate and a 0.1-0.2 mm thicklower balancing layer of laminate, plastic, paper or like materials.

The surface layer of a laminate floor is characterized in that thedecorative and wear properties are generally obtained with two separatelayers of paper, one above the other. The decorative layer is generallya printed paper and the wear layer is a transparent overlay paper, whichcomprises small aluminium oxide particles.

The printed decorative paper and the overlay are impregnated withmelamine formaldehyde resins, generally referred to as melamine resins.The impregnation is based on a two-step process where the paper in afirst step passes a bath of liquid melamine resin and in a second stepis dried to a sheet that is completely impregnated and covered with adry melamine resin. The decor paper that prior to impregnation has aweight of 60-80 gr/m2 comprises generally about 50 wt % of melamineformaldehyde thermosetting resins. The resin content in the overlay maybe even higher. Aluminium oxide particles are applied and incorporatedduring impregnation into the resin layer on one side of the overlaypaper that during pressing is in contact with the decor paper. Theimpregnated papers are laminated to a HDF core in large discontinuous orcontinuous laminate presses where the resin cures under high heat (about170° C.) and pressure (40-60 bars) and the papers are laminated to thecore material. An embossed press plate or steal belt forms the surfacestructure.

Digital printing may be used to print an image on the decorative papersheet or on the overlay. The digital printing is generally made prior toimpregnation and the flexibility that the digital technology providescannot be fully utilized. It would be an advantage if digital print maybe made after impregnation and on an impregnated paper or ifimpregnation could be avoided. Printing directly on a melamineimpregnated paper is difficult since the ink drops applied on themelamine layer bleed during printing and especially when the drymelamine layer becomes liquid and floats during the pressing operation.

Laminate floors may also have a surface of coated paper, foils orplastic foils and such foil materials are difficult to print digitally.A protective wear resistant transparent layer that generally is apolyurethane lacquer is used to covers the printed décor.

Luxury Vinyl Tiles, generally referred to as LVT floorings, are designedas a layered product made of thermoplastic PVC mixed with plasticizers.The name LVT is somewhat misleading since a major part of LVT floorshave a plank size with a wood pattern.

Thermal moulding based on calendar rolling or extrusion is used to formthe PVC layers. During the calendar rolling, the PVC material is heatedto its softening temperature and exposed to pressure between cylindersand cooled down.

The base layer or the core is made primarily of PVC mixed with chalkand/or limestone fillers and has a high quality printed decorative PVCfoil on the upper side. A transparent wear layer of vinyl with athickness of 0.2-0.6 mm is generally applied on the decorative foil.When PVC is heated it becomes soft like a paste and bonds under heat andpressure to other PVC materials but also to organic and inorganic fibresor minerals when cooled down to room temperature. The base layer, thedecorative foil and the transparent layer are fused or laminatedtogether with heat and pressure in continuous or discontinuous pressoperations. The laminated sheets are after pressing annealed to removestress and to achieve increased dimensional stability. Calendar rolling,pressing and annealing general takes pace at temperatures between 120°C.-160° C. Annealing may be combined with ageing at temperatures around25° C.-30° C. during a few days.

The decorative effects are obtained with a white decorative foil thatcovers a dark colour of the core and provides a base colour for therotogravure printing process where special solvent based inks are usedthat bond to the PVC surface. Such inks are difficult to combine with anenvironmental friendly, flexible and cost efficient printing process,especially when a digital printing method is used.

LVT floors offer several advantages over for example laminate floorssuch as deep embossing, flexibility, dimensional stability related tohumidity, moisture resistance and lower sound. Digital printing of LVTfloors is only on an experimental stage since it is difficult to printon the plastic foil but would, if introduced, provide major advantagesover conventional printing technology.

As a summary it may be mentioned that only small volumes of floor panelsare printed digitally, especially vinyl and laminate floorings, mainlydue to high cost of ink and high investment cost for the industrialprinters but also due to the fact that it is difficult to apply adigital print on the specific surface materials used in such flooringapplications.

Definition of Some Terms

In the following text, the visible surface of the installed floor panelis called “front side”, while the opposite side of the floor panel,facing the sub floor, is called “rear side”.

By “up” is meant towards the front side and by “down” towards the rearside. By “vertically” is meant perpendicular to the surface and by“horizontally” parallel to the surface.

By “binder” is meant a substance that connects or contributes to connecttwo particles or materials. A binder may be liquid, powder based, athermosetting or thermoplastic resin and similar. A binder may consistof two components that react when in contact with each other for examplewater and dry melamine.

By “digital printing” is meant a digitally controlled ejection of dropsof fluid that is used to position colorants in pre-defined patterns ontoa surface.

Known Technique and Problems Thereof

The general technologies, which are used by the industry to provide adigital print is described below. The methods may be used partly orcompletely in various combinations with preferred embodiments in orderto create a digital print according to this disclosure.

High definition digital ink jet printers use a non-impact printingprocess. The printer has print heads that “fire” drops of ink from theprint head to the surface in a very precise manner.

Industrial printers are generally based on a Single Pass Printingmethod, which uses fixed printer heads, with a width that corresponds tothe width of the printed media. The printed surface moves under theheads. Such printers have a high capacity and they are equipped withfixed print heads that are aligned one after each other in the feedingdirection. In general each print head prints one colour. Such printersmay be custom made for each application.

A suitable printer head has to be used in order to obtain a highprinting quality and speed. A print head has several small nozzles thatcan shoot and apply droplets of inks in a controlled way in a rasterpattern.

Thermal print head technology, generally referred to as bubble jetprinting, use print cartridges with a series of tiny chambers eachcontaining a heater. To eject a droplet from each chamber, a pulse ofcurrent is passed through the heating element causing a rapidvaporization of the ink in the chamber to form a bubble, which causes alarge pressure increase, propelling a droplet of ink out through thenozzle and to the surface intended to be printed.

Thermal technology imposes the limitation that the ink must beheat-resistant, generally up to 300° C. because the firing process isheat-based. This makes it very difficult to produce pigment based multicolour thermal heads.

Most commercial and industrial inkjet printers use the Piezoelectricprinter head technology, which is the major technology used in theflooring industry. A piezoelectric crystal material (generally calledPiezo) in an ink-filled chamber behind each nozzle is used instead of aheating element. When a voltage is applied, the piezoelectric materialchanges shape, which generates a pressure pulse in the fluid forcing adroplet of ink to be ejected from the nozzle. Piezo inkjet allows awider variety of inks and higher viscosity than thermal inkjet.

A lot of different ink types may be used. The main components arecolorants that provide the colour, a binder that bonds the colorants tothe surface intended to be printed and a liquid carrier that transfersthe colorant and the binder from the print head in well-defined smalldrops to the surface with a non-contact application method. The colorantis either a dye or pigment or a combination of both. The carrier fluidmay be water-based or solvent based. The carrier fluid evaporates andleaves the colorant on the surface. UV curable inks are similar tosolvent based inks but the carrier fluid cures when exposed to strong UVlight.

Pigments are very fine powder of solid colorant particles that aresuspended or dispersed throughout a liquid carrier. Pigment based inksare generally individually mixed together by using colour pigments andseveral chemicals.

Pigment inks are generally more light stable, especially when exposed toUV light, and more fade resistant than dye-based inks. They aretherefore used in almost all flooring applications. Water based digitalinks comprising colour pigments are especially suitable for flooringapplications and may provide a high quality printing method in manydifferent materials, provided that the materials have surface structurethat allows the liquid to partially penetrate into the upper part of thesurface.

Generally the pigments do not stick to a smooth surface. They aresimilar to sand particles and may be easily removed from most dry andsmooth surfaces. The water based carrier fluid is therefore generallymixed with small amounts of several other additives to provide specialink and print properties such as binders that provide the adhesion ofthe pigments to a surface, dot gain, pH level, drop formation, corrosionof the print head, fade resistance etc. The inclusion of resins thatserve as binder in the ink composition limits the possible amount ofpigments, as both components increases the ink viscosity.

Digital printing with water based ink comprising colour pigments is avery flexible and environmental friendly method that may provide a highquality print on for example a paper substrate but also in severalpowder based materials. It cannot be fully utilized in several flooringapplications where special materials such as thermoplastic materials ormelamine-impregnated papers are used as a substrate for the decor. Theink drops float and bleed when they hit a compact surface that is notable to absorb the liquid water based ink drops. It would be a majoradvantage if digital images may be formed with water based ink on suchcompact and dense surfaces.

Several methods are used to improve the printing properties of a digitalprint applied on smooth surfaces. Such methods comprise special inks andvarious types of coatings.

WO 2009/097986 describes a method to produce a special printing paper bycoating a fibre-based paper with open fibres in order to improve theprinting quality and to facilitate impregnation after the printing step.This method cannot be used when a print is applied on for example amelamine-impregnated paper where all fibres are covered with a melaminelayer.

WO 2001053387 describes a transfer method to form a print on a PVC tilebase. The method involves transferring the ink of a printed design,originally on a paper roll, to the tile base at the lamination nip. Thepaper is subsequently removed with a re-wind operation immediatelyfollowing the lamination. There is no description of the ink and papertype or that the print may be a digital print and the method does notgive any guidance of how a digital print may be obtained or transferredto a thermoplastic material.

US 20110180202 describes that digitally formed images such assublimation dyes may be heat transferred onto vinyl flooring materials.Heat activation occurs in temperatures between 160° C.-210° C. and thisis above the normal softening temperature of PVC material used in LVTfloors. An enhanced thermo-mechanical property or the flooring materialis therefore required that inhibits shrinkage from heat exposure. Thisis a major disadvantage and the printing method cannot be used in LVTfloors comprising conventional PVC materials.

So-called dry impregnation has been known and used for a long time. Animpregnated core paper is applied under an unimpregnated decor paper andthe impregnation of the decor paper is made during pressing when resinsfrom the overlay and the core paper penetrate into the decor paper. Thedecor paper may also be coated with a melamine resin on a lower side anda digital print may be applied on the raw upper side. Such productionmethods are expensive and have been mainly used for sample production.

WO 2013/032387 describes that separate layers such as a liquid melaminelayer or a powder layer comprising wood fibres and melamine powder maybe applied on a core. An unimpregnated raw paper is thereafter appliedon the core and the separate layer, prior to the digital printing step.The printed paper is during pressing impregnated from above by theresins from the overlay and from below by the resins in the separatepowder layer. Although this is a flexible and cost efficient method,there is still room for improvements especially related to propertiessuch as internal bond, production costs and production flexibility.

A disadvantage with know digital printing technologies is that inksfloats, especially water based ink, when ink drops are applied on asubstrate with dense and closed surface such as thermoplastic foils usedin LVT floors and resin impregnated papers used in laminate floors.

The above description of various known aspects is the applicants'characterization of such, and is not an admission that the abovedescription is prior art when the various technologies are used partlyor completely in various combinations.

OBJECTS AND SUMMARY

An objective of at least certain embodiments of the invention is toprovide a method to apply a digital print with preferably water-basedink comprising pigments on dense surfaces. A specific objective is toprovide a semi finished product based on a dense substrate that may beused as a print layer for a digital print. Another objective is toprovide a LVT floor or a laminate floor with a digitally printed decor.

The invention is based on a first principle where a print layer isformed by ink receiving particles and a pigment based digital print isformed on the print layer. The pigments and the print layer areincorporated into a decorative wear resistant surface comprising severallayers and adapted such that the pigments and the print layer arecompatible with the production methods that are used to form the surfaceand to bond the layers of the finished product. The principle may beused to produce a digitally printed floor panel with a decorative wearresistant surface comprising thermoplastic or thermosetting material.The principle may also be used to produce a semi-finished print basecomprising a thermoplastic or thermosetting surface with a print layercomprising particles that may be used to provide a digitally printeddecorative layer.

The invention is also based on a second principle wherein a digitalprint is applied on a substrate with a binder and powder (BAP) printingmethod where colour pigments or so called dry ink particles are appliedin dry form and bonded in patterns by digitally applied transparentblank ink drops. The printing method, the blank ink and the dry ink havebeen specially adapted to provide a high quality print on a densesurface such as a thermoplastic foil or a paper impregnated with athermosetting resin, for example, a melamine formaldehyde impregnatedpaper.

According to a first aspect of the invention a method of forming adecorative wear resistant layer, the method comprising:

-   -   providing a substrate comprising a thermoplastic material and a        transparent layer comprising a thermoplastic material,    -   providing a continuous print layer comprising particles on the        substrate or on the transparent layer,    -   printing a digital image comprising colour pigments on the print        layer,    -   bonding the print layer with the colour pigments to the        transparent layer and to the substrate with heat and pressure        such that the digital image is located between the transparent        layer and the substrate.

The transparent layer may be a thermoplastic foil, preferably a PVCfoil. The transparent layer is preferably a transparent wear resistantlayer.

The substrate may be a thermoplastic foil, preferably a PVC foil.

The substrate may be a core, preferably comprising a thermoplasticmaterial, preferably PVC, and fillers.

The print layer may, prior to printing, be bonded to the substrate or tothe transparent layer with a binder.

The print layer may, prior to printing, be bonded to the substrate orthe transparent layer, preferably with heat and pressure.

The print layer may be a paper layer or loose particles.

The particles may comprise fibres, preferably cellulose fibres, morepreferably at least partially bleached cellulose fibres.

The particles may comprise a thermoplastic powder, preferably a PVCpowder.

The print may be made with water-based ink, preferably comprising anacrylic binder.

The digital print may be made with a liquid binder that bonds a powdercomprising pigments.

The substrate may be a part of a building panel, preferably a floorpanel.

The substrate may be a part of a LVT floor panel.

According to a second aspect, a floor panel is provided comprising acore comprising a thermoplastic material, a decorative layer arranged onthe core, wherein the decorative layer comprises a thermoplasticmaterial, and a transparent layer arranged on the decorative layer,wherein the transparent layer comprises a thermoplastic material. Thedecorative layer comprises a digital print provided by ink comprisingpigments and an acrylic binder.

The decorative layer may further comprise particles to which thepigments are attached.

The particles may comprise fibres such as cellulose fibres or athermoplastic powder such as PVC.

According to a third aspect, a floor panel is provided comprising a corecomprising a thermoplastic material. A decorative layer is arranged onthe core, wherein the decorative layer comprises a thermoplasticmaterial, and a transparent layer is arranged on the decorative layer,wherein the transparent layer comprises a thermoplastic material. Thedecorative layer comprises a print layer arranged under the transparentlayer. The print layer comprises particles and colour pigments attachedto said particles.

The particles may comprise fibres such as cellulose fibres or athermoplastic powder such as PVC.

According to a fourth aspect, a flexible sheet shaped print base isprovided. The sheet shaped print base comprises a substrate and a printlayer, the substrate having two opposite surfaces, wherein one of saidsurfaces comprises a thermoplastic material and is essentially coveredwith the print layer. The print layer comprises particles comprisingfibres or a polymer material. The particles are bonded to said surface.

The substrate may be a thermoplastic foil, preferably a PVC foil.

The fibres may be cellulose fibres.

The polymer material may comprise a thermoplastic material such as PVC.

The surface may be completely covered with the print layer.

According to a fifth aspect, a flexible sheet shaped print base isprovided. The flexible sheet shaped print base comprises a substrate anda print layer. The substrate has two opposite surfaces, wherein one ofsaid surfaces comprises a paper impregnated with a thermosetting resinand is essentially covered with said print layer, and wherein the printlayer comprises cellulose fibres, said cellulose fibres being bonded tosaid surface.

The resin may be an amino resin such as melamine formaldehyde resin.

The fibres may be cellulose fibres.

The surface may be completely covered with the print layer.

The surface may comprise a base colour.

According to a sixth aspect, a method of forming a decorative wearresistant surface layer with a digital print head is provided. Themethod comprising:

-   -   providing a substrate comprising cellulose fibres, wherein the        substrate is impregnated with a thermosetting resin and        comprises a base colour,    -   printing a digital image on the substrate with a digital print        head that applies ink drops of a water based ink having a        viscosity exceeding about 10 cps on the substrate, and wherein        the ink drops are positioned in a raster pattern with a space        between each other,    -   applying cellulose fibres coated with pigments on the water        based ink drops and the substrate,    -   bonding a part of the pigment coated cellulose fibres to the        water based ink drops,    -   removing non bonded pigment coated fibres from the substrate,    -   applying a transparent layer comprising cellulose fibres on the        digital image such that the digital image is located between the        transparent layer and the substrate, and    -   bonding the substrate, the bonded part of the pigment coated        fibres and the transparent layer with heat and pressure.

The ink may comprise water based glycol or glycerine solution combinedwith a binder.

The thermosetting resin of the substrate may be melamine formaldehyderesin.

The substrate may be a paper layer impregnated with at least 40 wt% of athermosetting resin, preferably a melamine formaldehyde resin.

The pigment coated cellulose fibres may have a fibre thickness of about10-50 microns and a length of about 50-150 microns.

The pigment coated cellulose fibres may comprise a thermosetting resinor an acrylic binder.

According to a seventh aspect, a method of forming a decorative wearresistant surface layer with a digital print head is provided. Themethod comprising:

-   -   providing a thermoplastic substrate comprising a base colour,    -   printing a digital image on the substrate with a digital print        head that applies ink drops of a water based ink having a        viscosity exceeding about 10 cps on the substrate, and wherein        the ink drops are positioned in a raster pattern with a space        between each other,    -   applying thermoplastic particles comprising pigments on the        water based ink drops and the substrate,    -   bonding a part of thermoplastic particles to the water based ink        drops,    -   removing non bonded thermoplastic particles from the substrate,    -   applying a transparent layer comprising a thermoplastic material        on the digital image such that the digital image is located        between the transparent layer and the substrate, and    -   bonding the substrate, the bonded part of the thermoplastic        particles and the transparent layer with heat and pressure.

The water based ink may comprise a water based glycol or glycerinesolution combined with an acrylic binder.

The pigments may be bonded to the thermoplastic particles with anacrylic binder.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be described in connection toembodiments and in greater detail with reference to the appendedexemplary drawings, wherein,

FIGS. 1a-d Illustrate a LVT panel and methods to produce a digitallyprinted surface.

FIGS. 2a-d Illustrate a two-step digital printing method with bindersand powder.

FIGS. 3a-f Illustrate digital printing on a print layer.

FIGS. 4a-c Illustrate a method to form a print layer, to apply a digitalprint and to form a decorative surface layer.

FIGS. 5a-c Illustrate digital printing and print layers.

FIGS. 6a-e Illustrate digital printing on impregnated paper.

DETAILED DESCRIPTION

FIG. 1a shows a LVT flooring panel 1 which is intended to be installedfloating with a mechanical locking system comprising a tongue 10 and atongue groove 9 for vertical locking and a strip 7 with a lockingelement 8 in one edge that cooperates with a locking groove 14 in anopposite edge and locks in horizontal direction. The panel may also havestraight edges and may be installed by gluing down to the sub floor.

The core 5 may comprise one or several layers 5 a, 5 b, preferablycomprising a thermoplastic material. Said one or several layers 5 a, 5 bmay be made primarily of PVC mixed with 20-80% chalk or limestonefillers mainly in order to reduce material costs.

The core 5 has a substrate 4 on the upper side, which may be a printeddecorative foil 4 a comprising thermoplastic material suchpolyvinylchloride (PVC). This decorative foil 4 a may be very thin. Thedecorative foil 4 a may have a thickness of about 0.05-0.10 mm. Atransparent wear layer 3 comprising a thermoplastic material such as PVCis applied on the decorative foil 4 a. The transparent wear layer 3 mayhave a thickness of 0.2-0.6 mm. A balancing layer 6 may in someembodiments be applied on the rear side of the core 5 in order toprevent curving. The core 5 a, 5 b, the decorative foil 4, thetransparent layer 3 and the balancing layer 6 are fused together withheat and pressure in a continuous or discontinuous press operation.Binders may also be used to connect the core 5 to the upper layers. Theheat bonding of thermoplastic materials such as PVC may be made intemperatures between 130° C.-160° C. and with a pressure of 5-10 bars. Ahigher pressure may be used. The transparent layer may include a coating2 of polyurethane, which provides additional wear and stain resistance.The transparent wear layer 3 may be replaced with a polyurethane layer 2that is applied directly on the decorative foil 4 a. The transparentlayer 3 may also comprise transparent PVC powder that is pressed andfused to a decorative layer 4.

LVT floors with a PVC core comprising fillers and which are intended tobe installed floating with a mechanical locking system have generally athickness of 3-6 mm. The core 5 may be reinforced with glass fibres andmay comprise several layers 5 a, 5 b with different densities andmaterial composition. The lower side of the core 5 may comprise groovesor cavities in order to decrease the weight and to save material.

FIG. 1b shows a floor panel with a resilient decorative surface similarto the embodiment shown in FIG. 1a . The decorative wear resistantsurface 4, 3, may comprise a sub layer 11 that preferably is softer thanthe upper layers 3, 4 and that may provide sound reduction. The core 5is in this embodiment a HDF or MDF core 5 or a core 5 comprising acomposite material for example thermoplastic material, preferablypolyvinylchloride (PVC) or polypropylene (PP) mixed with wood fibres.Many other core materials may be used, preferably moisture resistantmaterials such as cement bonded particleboards or other types of mineralbased board material. The core 5 may even comprise a ceramic materialand the resilient upper layers may provide a soft surface with lowersound. Such panels with a ceramic core may also be installed floatingand may comprise a mechanical locking system.

The upper lip 9 a of the tongue groove 9 may be partially formed in thecore material 5. The upper layers 11, 4, 3 may also be used to formessentially the whole part of the upper lip 9 a. Such a locking systemcomprises a tongue groove 9 with a lower part formed in the corematerial 5 and an upper part, the upper lip 9 a, formed in a differentmaterial than the core 5. The upper lip 9 a comprises preferably a moreflexible material than the core 5 that may be more rigid. Such a lockingsystem may be used to decrease the thickness of the floor panel 1 andthe core 5.

FIG. 1c shows a Piezo print head 20 that applies a liquid pigment basedink 21 as small drops 22 on a substrate 4 that in this embodiment is apaper substrate 4 b. The liquid substance of the ink evaporates andpenetrates into the surface 15 of the paper substrate 4 b such that thepigments 23 are bonded to the surface 15 by the binder 30 of the ink 21that in a water based ink may be a liquid acrylic binder.

FIG. 1d shows a similar application on a dense surface such as a PVCfoil or a melamine formaldehyde impregnated paper 4 a. The liquidsubstance of the water based ink dispersion cannot penetrate into thedense PVC or into the melamine formaldehyde impregnated material and theink drops 22 float in an uncontrolled way and form clusters of inkdrops. The result is a low quality print that is not possible to use inflooring applications.

FIGS. 2a-2c show schematically that a digital print may be formed in twosteps with a Binder And Powder (BAP) printing method that has recentlybeen introduced in flooring application by Valinge Innovation AB, forexample, as described in U.S. patent application Ser. Nos. 13/940,572and 14/152,253, which hereby are incorporated by reference in itsentirety. A binder or a so called blank ink 30 that does not compriseany colorants is applied digitally and is used to bond a powder or a socalled dry ink 31 that comprises pigments 23.

FIGS. 2a and 2b show that a binder pattern 30 or image is formeddigitally by an ink head that preferably only applies a binder or socalled blank ink 30 on a substrate 4. A powder based dry ink 31, thatmay comprise small coloured particles for example pigments 23, isapplied randomly preferably in dry form such that the powder particlesare in contact with the binder pattern 30. FIG. 2b shows a preferredembodiment where dry ink 31 is scattered over the binder pattern 30.FIG. 2c shows that the binder 30 connects some particles of the dry ink31 that form the same pattern as the binder 30 and a digital print D isformed on the substrate 4 when non-bonded dry ink 31 is removed by forexample vacuum. Several colours may be applied and a multi colour highquality image may be formed in a cost efficient way since the costs forthe blank ink 30 and the dry ink 31 are considerable lower than forconventional ink comprising pigment dispersions. The BAP method mayprovide a digital print with the same or even superior quality asconventional digital printing technology. An advantage is that the printhead does not have to handle pigments that may clog the nozzles of theprint head.

FIG. 2d shows a BAP printing equipment. A digital printer 40 applies abinder 30 on specific and well-defined portions of the substrate as atransparent image and dry ink 31 in powder form is scattered on thebinder pattern with a scattering device 41. The binder may be dried orcured by IR or hot air with a curing device 42 and non-bonded dry inkparticles are removed by a powder-removing device 43. The substrate 4 isin this embodiment attached to an upper part of a core material 5 thatcomprise wood fibres or thermoplastic material.

The BAP printing may be combined with conventional ink jet printing. Themajor part of the colorants in a digital print may be applied with theBAP printing method and only some specific colours may be printed withthe ink jet printing method.

The BAP principle may be used to apply a well-defined powder layer witha uniform thickness and with a basic colour on the whole surface of asubstrate 4. Generally all types of particles may be applied and a widevariety of binders in liquid and dry form may be applied.

FIGS. 3a and 3b shows the basic principle to form a decorative wearresistant surface 4, 34, 23, 3 having a digital print comprisingpigments 23. A digital print with preferably a water based ink andpigments 23 is applied on an upper side of a print layer 34 as shown inFIG. 3a or on the lower side of the print layer 34 as shown in FIG. 3b .The digital print may be made with a conventional ink jet method or withthe BAP method. The lower substrate 4, preferably comprising a basecolour, and the upper transparent wear resistant layer 3 are laminatedto each other under heat and pressure with the print layer 34 and thepigments 23 positioned and laminated between the two layers. The lowersubstrate 4 is laminated to a core 5.

An advantage is that the digital print is applied on a print layer 34that may have properties adapted to create a high quality digital imageand that may be more suitable for the printing process than the denseand smooth surfaces of the materials used in the substrate 4 and in thetransparent layer 3. The print layer 34 may have favourable printing andbonding properties allowing a strong lamination to the different layersused to form the decorative wear resistant surface under heat andpressure.

The print layer may comprise many different particles such as organic orinorganic fibres or mineral particles in the principles described below.The particles may comprise fibres 31 such as cellulose fibres as shownin FIGS. 3a and 3b . The particles may comprise a thermoplastic materialsuch as PVC, preferably a thermoplastic powder such as PVC powder.

Several principles may be used to form the print layer 34.

-   -   1) According to a first principle, binders are used to connect        the particles to the substrate 4 or the transparent layer 3. The        BAP method may be used to connect and to form well defined        layers.    -   2) According to a second principle, the particles are attached        to a substrate 4 or to a transparent layer 3 with heat and        pressure. A wide range of particles will bond to a thermoplastic        material such as for example PVC if the thermoplastic material        is heated above the softening temperature and pressed against        the particles. A very well defined layer of connected particles        may be formed when the thermoplastic material is cooled.    -   3) According to a third principle, a print is applied and bonded        to an upper part of a loose particles layer that is used as a        print layer 34. One of the layers, preferably the transparent        layer 3, is pressed against the print that is bonded to the        layer preferably with heat and transferred together with some        particles from the print layer.    -   4) According to a fourth principle, a separate thin film shaped        print layer is used as a base for the print and the print layer        with the print is thereafter laminated and connected to the        layers.

FIG. 3c shows a digital print according to the first principle of theinvention that may be used to produce the decorative surface layer of aLVT panel. FIG. 3a shows a substrate 4 that may be a thermoplastic foilsuch as PVC foil 4 a. The substrate 4 may have a thickness of about0.1-0.6 mm. One surface 15 of the substrate 4 is coated with a binder30. The binder 30 may for example be a water based thermoplastic vinylpolymer such as PVA, PVAc, or a water based acrylic polymer emulsionthat preferably comprises gels in order to increase the viscosity or adispersion of vinyl acetate and ethylene. The binder 30 may be appliedin liquid form in one or several steps and with partial drying betweenthe applications in order to increase the viscosity. It is preferredthat the binder has a higher viscosity than the ink applied by the printhead. The particles or fibres 32, preferably bleached cellulose fibres,that after a pressing operation are substantially transparent, arescattered on the wet binder 30 and non-bonded fibres are removedaccording to the BAP principle.

A Piezo print head 20 is used to apply ink drops 22 on the print layer34. The print layer 34 prevents floating of ink drops 22 after printingand bleeding of the pigments 23 during lamination when for example heatand pressure is used to fuse the foil to a core comprising thermoplasticmaterial, preferably PVC, and a transparent protective layer to the foil4 a during production of a LVT panel. A high quality digital print and astrong bonding of the layers may be obtained even in the case when waterbased ink 21 preferably comprising an acrylic binder is used.

The print layer is preferably applied on a decorative foil 4 a thatcomprises a base colour. The print layer and the digital print may alsobe applied on the lower side of a transparent wear layer.

PVC layers in a LVT panel are fused together with heat and pressure. ThePVC material is not liquid and cannot penetrate into a fibre layer.Fibres that during pressing under high temperature, for example 130°C.-160° C., are in contact with a PVC layer will be fused to the surfaceof the decorative foil 4 a or of the transparent layer.

Preferably, the fibre based print layer is thin, for example having athickness of 0.003-0.10 mm, especially when PVC foils and cellulosefibres are used.

Preferably, the binder bonds the majority of the fibres. Loose fibresmay cause delamination. A thick fibre layer will generally not givesufficient bonding between the decorative PVC foil 4 a and thetransparent wear layer except when a binder 30 is used that duringlamination may penetrate into the fibres. The bonding betweenthermoplastic layers is preferably obtained by the binder 30 thatconnects the fibres 32 to one of the layers and the acrylic binder inthe ink 21 that is applied on the fibres during printing and that bondsthe fibres to the other layer during lamination. Two binders arepreferably used to connect PVC layers on each side of the fibres—a firstbinder 30 applied prior to the application of the fibres and a secondbinder applied on the fibres by the ink 21 during the digital printing.

It is preferred that a fibre based print layer 34 has a thickness ofabout 0.03-0.10 mm or a weight of about 10-30 g/m2.

In most applications when a full print is applied over the whole surfacesufficient amount of binders will be applied on the fibres 32 by thebinder in the ink 21. In some applications additional binders may beneeded in order avoid delamination. Such binders may be applied by aseparate row of print heads that applies blank ink comprising a binder,preferably an acrylic binder, on the fibres. Binders may also be appliedon both layers.

The method may be used to apply a print layer in line on a foil that isthereafter printed digitally in a second production step. The method mayalso be used to produce special coated foils or papers that constitute aprint base 35 and that may be supplied in rolls or as sheets to afactory where the final digital printing takes place.

FIG. 3d shows that similar methods may be used to form a print layer 34on for example a paper 4 b that is impregnated with a thermosettingresin 24 for example a melamine formaldehyde resin. The paper 4 b may bea decorative paper with a base colour and the print layer 34 is appliedon the coloured surface. It may also be an overlay paper and the printlayer is applied on a surface that after lamination constitutes thelower side of the overlay. The bonding may be obtained by just coatingthe dry melamine surface with water. The dry melamine formaldehyde layermelts and bonds the particles 32, preferably the fibres to the melamineformaldehyde impregnated surface. The melamine formaldehyde impregnatedpaper, which generally comprises a resin content of 50% and more iscovered by an open fibre structure, preferably bleached cellulosefibres, that preferably comprise much lower resin content than the papersubstrate. The resins in the upper fibres that are intended to beprinted are only needed to bond the fibres to the paper during printingand the resin content may be lower than about 10 wt %. The upper fibresmay be essentially free from resins and the ink drops comprisingpigments 23 may be applied directly on the fibres. This eliminatesfloating and bleeding during lamination. Melamine may also be applied inliquid form on the dry melamine layer. The application of the binder andthe powder may be made as a separate production step after impregnationor in line in connection with the impregnation. The thickness of a fibrebased print layer is less essential when melamine impregnated papers 4 bare used as a substrate since melamine floats during lamination and allfibres are automatically impregnated and bonded by the liquid melamine.

Many different organic and inorganic particles and binders may be usedto form a print layer 34 on a substrate and the particles and bindersmay comprise pigments or other types of colorants. It is however anadvantage in some applications if the particles are such that they aretransparent or at least semi transparent when heat and pressure isapplied during lamination. The base colour of the substrate may be usedas one of the colours in the print and the digitally applied image willnot be disturbed by the particles that form the print layer. Theparticles and the binder should be adapted to the materials and methodsthat are used to connect the decorative layer to a panel core and toprotect the print from wear.

Particles that are compatible with several polymer materials andespecially thermoplastic material such as PVC but also thermosettingresins are for example cellulose fibres, kaolin, talk, chalk, limestone,carbonate, feldspar, glass fibres, aluminium oxide, silicon carbide,silica and similar minerals.

Separate polymer materials may be used as binders to connect particlesto a thermoplastic foil material such as a PVC foil. The bonding canalso take place in line with the foil production and preferably PVC inliquid form may be applied on the foil surface and may connect theparticles.

Fibres and other particles may also be connected to a PVC material forexample a PVC foil without binders. The foil may be heated and pressedagainst a particle layer and particles that are in contact with the hotfoil will be connected. A thin and very well defined layer of particlesmay be applied by the hot pressing method and a strong bonding may beobtained.

FIG. 3e shows a substrate 4 that in this embodiment is a PVC foil 4 a.Thermoplastic particles 33 preferably PVC powder, for example VESTOLIT,are applied on a binder that may be a water based thermoplastic polymerfor example PVA, PVAc or an acrylic polymer emulsion. VESTOLIT powdergives a strong bonding between individual particles and PVC layers whenheat end pressure is applied and the print layer thickness may be muchlarger than when fibres or minerals are used as a print layer. Theporous microstructure of the plastic particles forms a print layer thatprevents floating of the ink drops and pigments 23 are attached to theparticles. PVC powder may have a basic colour but may also betransparent such as VESTOLIT when fused together with heat and pressure.A second powder layer 33 b comprising thermoplastic particles may beapplied over the digital print and may form a protective wear layer thatmay replace the transparent foil 3. The second layer 33 b may alsocomprise a binder and preferably also wear resistant particles such asaluminium oxide particles. The layers may be applied and bonded to thesubstrate by the BAP method as dry ink 31.

The above-described methods may be combined. The particles may forexample comprise a mix of fibres and PVC powder such as VESTOLIT andsuch a mix may provide an increased bonding between the layers. Thebonding properties of a the particles in a print layer may be increasedif for example vinyl based polymer powder such as VINNAPAS is mixed withthe particles.

FIG. 3f shows that a LVT floor panel may have an upper core layer 5 acomprising PVC, fillers and pigments 23 and this core layer 5 a mayreplace the decorative foil as a colour barrier against the other partsof the core 5 b that have an undefined colour that may telegraph troughthe printed pattern. The print layer 34 comprising plastic particles 33is applied directly on a core layer 5 a and ink drops comprisingpigments 23 are applied on the plastic particles 33.

FIG. 4a shows schematically equipment that may be used to form the printlayer 34 or a print base 35 in preferably four production steps. Theequipment comprises a binder application device 41, a scattering device42, a curing device 43 and a powder removing device 44. The binder 30may be applied with the binder application device 41 that is for examplea roll coating in one or several steps on the upper surface 15 of thesubstrate 4. Primers may also be used. The rolls may have a structuredsurface such that a raster shaped binder pattern is formed. The bindermay also be applied by spraying or digitally with a Piezo print head.Roll coating is preferred in several applications since the binder mayhave a much higher viscosity than when spray nozzles or digital Piezoprint heads are used. In a second step the powder, in this preferredembodiment fibres 32, are scattered on the wet binder 30 with thescattering device 42. The binder is in a third step cured with thecuring device 43 that may comprise IR light, hot air, UV light etc.depending on the binder. Finally in a fourth step the non-bonded fibres32 are removed with the powder removing device 44 where vacuum andairstreams may be used and a substrate 4 with a print layer 34 isformed.

Several other methods may be used. Drying or curing of the binder maytake place when non-bonded particles have been removed. The powder maybe applied in a precise manner and removal of non-bonded powder may beexcluded. Scattering may be replaced with application methods where thesubstrate with the binder is pressed against powder or where thesubstrate passes a container filled with powder.

The substrate 4 with the print layer 34 may be used as a semi finishedprint base 35 product and may be transported in rolls or sheets toanother location where the digital print is made. The print layer 34 andthe print base 35 may also be formed in line with the digital printingoperation.

FIG. 4b shows digital printing on the print layer 34 or on a print base35 with a digital printer 40 comprising five print heads 20, eachcomprising one colour.

The print layer 34 comprises in this embodiment fibres 32 that arebonded to the substrate 4 with a binder 30. The digital print may bemade with conventional printing methods where pigments 23 are includedin the liquid ink applied by the print heads 20. The digital print mayalso be made partly or completely with the BAP printing method asdescribed above where liquid blank ink comprising a binder and dry inkcomprising pigments are applied in two separate steps.

FIG. 4c shows an upper part of an LVT panel 1. A thermoplastic foil 4 asuch as a PVC foil with a print layer 34 and a digital print comprisingpigments 23 is positioned between the core 5 and the transparent wearlayer 3. Alternatively, the print layer 34 and the digital print withthe pigments 23 are positioned on the lower side of the transparentlayer 3 (not shown). The very thin print layer 34 will be surrounded bythe binders 30 from the print layer and the ink that during pressing maypenetrate into the print layer such that a strong lamination of thelayers may take place. The pigments 23 are firmly connected to the printlayer and bleeding may be avoided. The wear layer 3 comprises apolyurethane layer 2 on the upper side.

According to one aspect of the invention a LVT floor panel is providedhaving a core 5 comprising a thermoplastic material and fillers, anupper transparent surface layer 3 and a decorative layer 4 between thecore 5 and the transparent layer 3. The decorative layer 4 comprises adigital printed decor preferably provided by water-based ink comprisingpigments and acrylic binder.

According to another aspect of the invention a LVT floor panel isprovided having a core 5 comprising a thermoplastic material andfillers, an upper transparent surface layer 3 and a decorative layer 4between the core 5 and the transparent layer 3. The decorative layer 4comprises fibres 32, preferably cellulose fibres or minerals.

FIG. 5a shows a method to form the print layer 34 and the print base 35according to the second principle of the invention. Particles arescattered on a on a conveyor or a carrier by a scattering device 42. Asubstrate 4 that may be a thermoplastic foil preferably a PVC foil isheated by preferably a hot press roller 45 and pressed againstparticles, for example fibres 32, preferably cellulose fibres, such thata thermal bond is accomplished between the particles 32 and thesubstrate 4.

Hot bonding may also be used to form a print layer in applications whereparticles are scattered on a hot core layer preferably comprisingpigments. A hot wood plastic composite panel comprising PVC or PP mixedwith wood fibre based fillers may also be scattered with particlespreferably fibres after the extrusion when the panel is still hot.

FIG. 5b shows a method to form the print layer according to the thirdprinciple of the invention. Particles, preferably fibres 32,thermoplastic powder 33 such as PVC powder or minerals are for examplescattered as a continuous powder layer on a conveyor and they are notconnected to a substrate. The continuous powder layer is used as a printlayer 34 for the digital print that is applied by a digital printer 40on the loose particles of the continuous powder layer 34. The digitalprint may be printed by an ink comprising a pigment dispersion. Athermoplastic foil that may be a substrate 4 comprising a base colour ora transparent foil 3 is heated and pressed against the pigments 23 thatare transferred to the thermoplastic foil together with particles fromthe print layer 34, for example fibres 32 or thermoplastic powder 33. Itis an advantage if the pigment dispersion in the ink comprises acrylicresins that provide a strong bond between the pigments and thethermoplastic foil. Such method to transfer a digital print frompowder-based particles may also be used without hot bonding. A melamineformaldehyde paper may comprise a wet melamine binder and may be pressedagainst the print with the powder. A thermoplastic foil comprising abinder may also be pressed against the print.

FIG. 5c shows a method to form the print layer 34 and the print base 35according to a fourth principle of the invention. The print layer 34 isa paper layer preferably a non-impregnated raw overlay paper comprisingfibres that are transparent or semi transparent after lamination. Adigital print is applied preferably on a side of the print layer 34 thatis laminated to the upper transparent layer 3 and a lower substrate 4.The transparent layer 3, the print layer 34 and the substrate 4 arelaminated to a core 5. It is an advantage if the paper is thin and has aweight of about 40-60 gr/m2. The bonding strength may be increased iffor example blank ink comprising an acrylic binder is applied digitallyor with roll coating on one or both sides, preferably after the printingstep. The paper may be replaced by a non-woven material made from longfibres, bonded together by chemical, mechanical, heat or solventtreatment.

The hot bonding and lamination of the layers according to the second,third and fourth principles is preferably made at temperatures of about120° C.-160° C. The four described principles may be combined. A firstlayer of particles may be applied for example with hot bonding and asecond particle layer may be applied by the use of a binder.

The particles may in all embodiment of the invention comprise colourpigments that may be used to provide a print layer with a base colour.

FIG. 6a shows a preferred embodiment, similar to the embodiment shown inFIG. 3d , comprising a core 5, and a decorative wear resistant surfacelayer 12 comprising a paper substrate 4 b impregnated with athermosetting resin 24, preferably a melamine formaldehyde resin 24, aprint layer 34, preferably comprising cellulose fibres and pigments 23applied by a digital print head on the print layer 34. The print iscovered by a wear layer 3 which in this embodiment is a conventionaltransparent overlay impregnated with a melamine formaldehyde resin 24.The overlay 3 comprises wear resistant particles 25. The three layersare heated, pressed and laminated to the core 5. This preferredembodiment may be used to form a print base 35. Cellulose fibres 32 areapplied as a print layer 34 and bonded to a paper substrate 4 bimpregnated with a thermosetting resin 24, preferably a melamineformaldehyde resin. The cellulose fibres 32 may be bonded to theimpregnated paper 4 b with a thermosetting binder, preferably a melamineformaldehyde resin, that may be applied as dry powder or as a liquid.The paper 4 b and the applied cellulose fibres 32 may comprise a basecolour. The fibre type and/or the fibre size and/or the fibreorientation are preferably different in the print layer and the papersubstrate 4 b. The fibres have preferably a length of about 50-300microns and a thickness of about 10-50 microns. The paper fibres may beadapted to cover a core 5 and provide a strong lamination to the coreand the cellulose fibres in the print layer 34 may be adapted to receiveand bond ink drops. Preferably, the fibres in the print layer 34 areshorter and comprise a lower amount of resins than the fibres in thepaper substrate 4 b that may be longer and that may be coated with ahigher resin content. The resin content in the paper substrate ispreferably at least about 40 wt %.

FIGS. 6b-6d show that the BAP method may be used to apply a digitalprint directly on a dense substrate without a print layer. A preferredembodiment comprise a core 5, a paper substrate 4 b impregnated with athermosetting resin 24, preferably a melamine formaldehyde resin and adigital print applied on the substrate 4 b by the BAP method. Theprinting method, the blank ink or the binder and the dry ink or thecolorants have been specially adapted to provide a high quality print ona dense surface, preferably a paper comprising a base colour andimpregnated with a melamine formaldehyde resin or a thermoplastic foil.

A first problem that has to be solved is the floating of the ink drops22 when they hit for example a dense melamine formaldehyde impregnatedsurface, especially a surface that comprises a high content of melamineformaldehyde resin exceeding 40 wt % of the impregnated paper. This maybe solved with blank ink having a high viscosity and with a printingmethod that positions the ink drops preferably side by side and spacedfrom each other in a raster pattern such that the ink drops are not incontact with each other. Clusters of ink drops attracted to each otherby the surface tension will be avoided.

A suitable blank ink that preferably may be used in a high viscosityprint head designed to operate with a viscosity of about 10-12 cps andhigher such as a Fuji print head may be water based glycol/glycerinesolution combined with a binder. A suitable blank ink for a highviscosity print head may for example comprise about 20% water, 60%glycerine, 10% diethylene glycol and 10% binder, preferably a bindercomprising a thermally cross linkable acrylate copolymer dispersion.

A second problem that has to be solved is bleeding of the pigmentsduring pressing when the melamine resin is in a liquid stage. Thisproblem may be solved with pigments that are connected to a pigmentcarrier such as wood fibres 32 that are not floating since they arepressed against the paper substrate 4 b during pressing and curing.

A suitable dry ink comprises preferably cellulose fibres 32 coated withpigments bonded to the fibre surface with a thermosetting resin,preferably a melamine resin or an acrylic binder.

Such pigment bonding may be obtained with production methods where thepigments and fibres in a first step are mixed to a powder. In a secondstep water comprising for example melted melamine resins or a waterbased acrylic binder is mixed into the dry powder and the wet mix isthereafter heated and dried. In a third step the dried powder is milledand sieved such that a suitable particle size is obtained.

The coated and sieved fibres have preferably a length of about 50-150microns and a thickness of about 10-50 microns. Such fibres are easy toapply with scattering and to remove with airstreams and they provide ahigh resolution print. The fibres will also absorb a substantial part ofthe liquid ink and floating of ink drops will be eliminated after theapplication of the dry ink.

The pigment coated and sieved fibres are preferably in a fourthproduction step mixed with dry melamine particles in powder form thatmelt and bond the coated fibres to the surface of the impregnated paperwhen they are in contact with the liquid blank ink drops.

FIG. 6b shows blank ink drops 22 applied on a paper substrate 4 bimpregnated with a thermosetting resin 24, preferably a melamineformaldehyde resin. The ink drops 22 are applied in a raster pattern andspaced from each other with a space S that may be about 10 microns orlarger.

FIG. 6c shows dry ink particles comprising pigment-coated fibres 32applied on the blank ink drops 22 and the paper substrate 4 b.

FIG. 6d shows the paper substrate 4 b when non-bonded dry ink particleshas been removed by for example air streams such that only coated fibres31 bonded by the blank ink drops 22 are attached to the substrate 4 b.Individual fibres 32 may be connected to several ink drops 22. Thefibres will overbridge the space S and the space S between the ink drops22 will not disturb the digital image D.

FIG. 6e shows pressing and curing of the decorative wear resistantsurface layer 12. The core 5 comprises a balancing layer 6 that may be apowder mix of wood fibres 32 and melamine powder 24 c. In someapplications a similar powder layer 32 may be applied under the papersubstrate 4 b in order to increase the impact resistance and to allowforming of a deep embossing. The digital print D may be covered by awear layer 3 which in this embodiment may be a conventional transparentoverlay impregnated with a melamine formaldehyde resin 24. The overlay 3comprises wear resistant particles 25. The wear layer 3 may also be apowder overlay comprising wear resistant particles 25 and binders 24.The layers and the digital print D are heated pressed by an upper 46 aand a lower 46 b press table and laminated to the core 5.

The above-described BAP printing may also be used to form a digitalprint on a foil. The substrate may comprise a thermoplastic foil and thedry ink 31 may comprise thermoplastic particles and pigments. Pigmentsmay be bonded to plastic particles with an acrylic binder. Pigments mayalso be incorporated into the thermoplastic particle body. The plasticparticles have preferably a diameter of about 50-150 microns.

The BAP printing may be applied on the substrate in a separate operationor may be applied in line when the substrate is positioned on a corematerial.

The BAP method may also be used to apply a print layer on a surface. Ablank ink raster pattern may be applied on substantially the wholesurface of a foil or a paper and particles may be bonded such that aprint layer with a well-defined layer thickness may be formed whennon-bonded particles are removed.

1. A method of forming a decorative wear resistant layer, the methodcomprising: providing a substrate comprising a thermoplastic materialand a transparent layer comprising a thermoplastic material, providing acontinuous print layer comprising particles on the substrate or on thetransparent layer, printing a digital image comprising colour pigmentson the print layer, and bonding the print layer with the colour pigmentsto the transparent layer and to the substrate with heat and pressuresuch that the digital image is located between the transparent layer andthe substrate.
 2. The method as claimed in claim 1, wherein thetransparent layer is a thermoplastic foil.
 3. The method as claimed inclaim 1, wherein the substrate is a thermoplastic foil.
 4. The method asclaimed in claim 1, wherein the substrate is a core.
 5. The method asclaimed in claim 1, wherein the print layer prior to printing is bondedto the substrate or the transparent layer with a binder.
 6. The methodas claimed in claim 1, wherein the print layer prior to printing isbonded to the substrate or the transparent layer.
 7. The method asclaimed in claim 1, wherein the print layer is a paper layer or looseparticles.
 8. The method as claimed in claim 1, wherein the particlescomprise fibres.
 9. The method as claimed in claim 1, wherein theparticles comprise a thermoplastic powder.
 10. The method as claimedclaim 1, wherein the print is made with water based ink.
 11. The methodas claimed in claim 1, wherein the digital print is made with a liquidbinder that bonds a powder comprising pigments.
 12. The method asclaimed in claim 1, wherein the substrate is a part of a building panel.13. The method as claimed in claim 1, wherein the substrate is a part ofa LVT floor panel.
 14. A floor panel, comprising a core comprising athermoplastic material, a decorative layer arranged on the core, whereinthe decorative layer comprises a thermoplastic material, and atransparent layer arranged on the decorative layer, wherein thetransparent layer comprises a thermoplastic material, wherein thedecorative layer comprises a digital print provided by ink comprisingpigments and an acrylic binder.
 15. The floor panel according to claim14, wherein the decorative layer further comprises particles to whichthe pigments are attached.
 16. The floor panel according to claim 15,wherein the particles comprise fibres or a thermoplastic powder.
 17. Afloor panel, comprising a core comprising a thermoplastic material, adecorative layer arranged on the core, wherein the decorative layercomprises a thermoplastic material, and a transparent layer arranged onthe decorative layer, wherein the transparent layer comprises athermoplastic material, wherein the decorative layer comprises a printlayer arranged under the transparent layer, the print layer comprisingparticles and colour pigments attached to said particles.
 18. The floorpanel according to claim 17, wherein the particles comprise fibres or athermoplastic powder.
 19. A flexible sheet shaped print base, comprisinga substrate and a print layer, the substrate having two oppositesurfaces, wherein one of said surfaces comprises a thermoplasticmaterial and is essentially covered with the print layer, wherein theprint layer comprises particles comprising fibres or a polymer material,said particles being bonded to said one of said surfaces.
 20. Theflexible sheet shaped print base as claimed in claim 19, wherein thesubstrate is a thermoplastic foil.
 21. The flexible sheet shaped printbase as claimed in claim 19, wherein the fibres are cellulose fibres.22. The flexible sheet shaped print base as claimed in claim 19, whereinthe polymer material comprises a thermoplastic material.
 23. Theflexible sheet shaped print base as claimed in claim 18, wherein saidone of said surfaces is completely covered with said print layer.
 24. Aflexible sheet shaped print base, comprising a substrate and a printlayer, the substrate having two opposite surfaces, wherein one of saidsurfaces comprises a paper impregnated with a thermosetting resin and isessentially covered with the print layer, wherein the print layercomprises cellulose fibres, said cellulose fibres being bonded to saidone of said surfaces.
 25. The flexible sheet shaped print base asclaimed in claim 24, wherein the resin is a melamine formaldehyde resin.26. The flexible sheet shaped print base as claimed in claim 24, whereinthe fibres are cellulose fibres.
 27. The flexible sheet shaped printbase as claimed in any ono of claims claim 24, wherein said one of saidsurfaces is completely covered with the print layer
 28. The flexiblesheet shaped print base as claimed in claim 24, wherein said one of saidsurfaces comprises a base colour.
 29. A method of forming a decorativewear resistant surface layer, the method comprising: providing asubstrate comprising cellulose fibres, wherein the substrate isimpregnated with a thermosetting resin and comprises a base colour,printing a digital image on the substrate with a digital print head thatapplies ink drops of a water based ink having a viscosity exceedingabout 10 cps on the substrate, and wherein the ink drops are positionedin a raster pattern with a space between each other, applying cellulosefibres coated with pigments on the water based ink drops and thesubstrate, bonding a part of the pigment coated cellulose fibres to thewater based ink drops, removing non bonded pigment coated fibres fromthe substrate, applying a transparent layer comprising cellulose fibreson the digital image such that the digital image is located between thetransparent layer and the substrate, and bonding the substrate, thebonded part of the pigment coated fibres and the transparent layer withheat and pressure.
 30. The method as claimed in claim 29, wherein theink comprises water based glycol or glycerine solution combined with abinder.
 31. The method as claimed in claim 29, wherein the thermosettingresin of the substrate is melamine formaldehyde.
 32. The method asclaimed in claim 29, wherein the substrate is a paper layer impregnatedwith at least 40 wt % of the thermosetting binder.
 33. The method asclaimed in claim 29, wherein the pigment coated cellulose fibres have afibre thickness of about 10-50 microns and a length of about 50-150microns.
 34. The method as claimed in claim 29, wherein the pigmentcoated cellulose fibres comprise a thermosetting resin or an acrylicbinder.
 35. A method of forming a decorative wear resistant surfacelayer, the method comprising: providing a thermoplastic substratecomprising a base colour, printing a digital image on the substrate witha digital print head that applies ink drops of a water based ink havinga viscosity exceeding about 10 cps on the substrate, and wherein the inkdrops are positioned in a raster pattern with a space between eachother, applying thermoplastic particles comprising pigments on the waterbased ink drops and the substrate, bonding a part of thermoplasticparticles to the water based ink drops, removing non bondedthermoplastic particles from the substrate, applying a transparent layercomprising a thermoplastic material on the digital image such that thedigital image is located between the transparent layer and thesubstrate, and bonding the substrate, the bonded part of thethermoplastic particles and the transparent layer with heat andpressure.
 36. The method as claimed in claims 35, wherein the waterbased ink comprises a water based glycol or glycerine solution combinedwith an acrylic binder.
 37. The method as claimed in claim 35, whereinthe pigments are bonded to the thermoplastic particles with an acrylicbinder.